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Mortar, mortero or mud: why you need to know how to work with this ancient material

The use of mortar in construction has been around since around 6500 B.C., and still has a place in today’s construction projects.

Martin Brookes, Heritage Marble & Tile, Inc., giving a talk on best practices at Coverings.

The ability to fix and shape substrates makes it a perfect material to fine tune and flatten to achieve a perfect setting surface for tile. The skill is an art form, but in today’s tile craft, its importance has dimmed in light of other quicker, more cost-effective systems. These new technologies do have a place, but will never take the place of a mortar bed in some applications.

Contractors around the country may approach the use of mud differently, but the outcome is the same: a true, plumb, flat surface.

At Heritage Marble & Tile, Inc., in Mill Valley, Calif., we have just completed a complicated installation of glass mosaic and handcrafted tile that could not be accomplished without the use of mortar beds. Recently, our mortar beds have been restricted to floor surfaces, but occasionally we are asked to do a complicated installation that requires the use of mortar beds on a vertical surface. We have a very talented workforce who are skilled in doing mortar beds; this has separated us from the pack. I would highly recommend that you keep the skill alive through training your installers, because you never know when you might need to use it.

When I scroll through Facebook groups, I see a lot of discussion around mortar beds, with some  installers never having created a mortar bed and others doing it on a regular basis. 

At Heritage Marble & Tile, we create mortar beds on an as-needed basis. We like to take a system approach in many cases, but the fact that we can do it when needed opens the marketplace for more artisan projects.

Mike DeGuisti, president of NTCA Five-Star Contractor Terra-Mar in Oklahoma City, said, “Mud work is becoming a lost art, at least in my part of the country. I remember coming up in the trades when floors were all floated, either direct-bond or with a cleavage membrane and walls and ceilings were all lath and plaster. Floating of floors – especially in areas with drains – is the only way to achieve the proper slopes. Floating of the walls allowed us to have perfect tile layouts without all the squirrely cuts to fix the walls we receive in today’s construction practices.”

The Grotto is a complicated project involving glass mosaic and handcrafted tile that Heritage Marble & Tile, Inc., just completed. It could have not have been accomplished without the use of mortar beds.

LATICRETE Mud Event Circa 2015

Around 2015, LATICRETE held a mortar workshop in Corona, Calif., for the Tile Geeks Facebook group members from all around the country to either mentor or learn how to do mud. “It was a well- attended event with installers who had never done mud work now implementing it in their workplace on a regular basis,” DeGiusti said.

One of the attendees was Robert Davis, owner of Davis Solutions from the Pacific Northwest, who’s been in the trade for 13 years.

“When I began as a helper, every shower we built was a B-415 (although I did not know it at the time),” he said. “I chopped a lot of deck mud in a tub that has since been passed down to me by Jeremy VonRuden. For a while, I had no notion that wall mud even existed.”

At the event, Davis got some helpful hands-on training from Jack Hamilton, Shaun Haley, and “a lot of other lifelong mudders,” he said. “I got a taste for mud work, and have been dabbling in it since. I still float almost every shower pan, and technology has speeded up the process. Now I use a Bucket Mortar Mixer, and my kids use the old mud tub as a sled in the winter. Topical waterproofing advancements have also shaved install time.

“I have successfully floated interior walls for thin glass mosaic, which would have been a much more daunting task without tremendous support from the MUD Facebook group,” he explained.  “They held my hand (digitally) through the process, and a few repetitions have boosted my confidence. Mud is an ability that I need in my repertoire, and I’ll continue to sharpen it.”

 Davis is staunchly pro-mud. “Our trade needs mud,” he said. “The awareness of mud work is more so today than ever – and so is the recognition that the art needs to be learned. Anyone interested in learning to float should consider traveling to Fresno, Calif., for an annual MUD event, where veteran and aspiring mudders alike meet to sling mud in a fun and educational environment. More information is available at themudevent.com.”

In 2015, members of the Tile Geeks Facebook group from across the country descended on a mud class in Corona, Calif., that LATICRETE offered, to either mentor or learn how to do mud. 

Flexibility, creativity and perfection

John Cox of NTCA Five-Star Contractor Cox Tile in San Antonio, Texas, is a long-time mud proponent, who has used the one-coat method of applying mud in his business for 45 years. 

“We use mud as an advantage in bidding work where demanding and costly materials are used in some of the homes we work on,” he said. “A flat, level and plumb surface is critical in these installations. Sometimes we have to build arches on shower jambs and the only way to achieve this is with mud. It is paramount to educate the customer as to why.”

Cox said he is seeing more interest in learning the art of mud work. “Tile men and women are aggressively seeking the training and knowledge in understanding the importance and benefits of mud work,” he said. “We have built Jacuzzi tubs with mud that simply cannot be built with any other product. You have so much more flexibility in building the walls flat and level, instead of using the newer technology and spending the time rendering walls to make them flat and level. Unfortunately with the lack of skill in some framers – and green lumber – you have all kinds of walls that are either warped, humped or out of level.”

When seeking absolute perfection in the installation, mud is the material of choice. “Small penny rounds and other smaller tiles are challenges since they show every imperfection in the substrate, such as round corners,” Cox said. “We do all of our showers, tubs and floors with mud. We recently had a customer request some of the newer technology of products. But after explaining the benefits of ‘old school mud’ he agreed to go with our method. There may be substitutions but there is no equal.”

“Tile men and women are aggressively seeking the training and knowledge in understanding the importance and benefits of mud work,” said John Cox, of NTCA Five-Star Contractor Cox Tile in San Antonio.

For flat floors, use mud

Cox emphasized that mud is the only way to achieve a perfectly flat floor, especially when working with large concrete on-grade floors. Building a mud floor allows you to create a flat substrate to meet ANSI standards of floor flatness. 

It especially comes into play in creating level transitions from different elevations, or substrates with different finished heights, he said. “This is achieved by starting with the correct depth off the floor and floating the floor off of that point,” he explained. “Mud on floors allows you to float to a drain or multiple drains or on a balcony to create the proper drain of 1/4” per foot to the edge.”

It’s also important to build in movement accommodation when working with mud. “One thing to satisfy EJ 171 is we install 1/4” foam around the perimeter so the mud is not coming in contact with the wood plates on floors,” Cox added. “Most think EJ 171 pertains to only the tile and grout. Tenting can occur when moisture comes in contact with the plates if this is not protected and
honored.”

Mud may be more affordable in the long run, as well. “I always tell my builders to err deeper instead of shallower for floors or walls,” Cox said. “An extra layer or coat of mud is far cheaper than reframing a wall or chipping concrete on a floor.” 

Navigating the limitations of mud

Mud may be miraculous, but the knowledge of methods is crucial in executing mortar beds. That’s why the TCNA Handbook for Ceramic, Glass and Stone Tile Installation should be studied and understood beforehand for walls and floor methods.

As versatile as mud work is, the limitations of the mortar beds are not always fully understood. One needs to follow the guidelines to create a plumb, true substrate preparation to avoid any complications that may arise from the improper application of the methods.

Heating up the house

Manufacturers offer advice for successful floor warming installations

Electric underfloor heating systems have come a long way since the old days. They offer comfort underfoot, ease of installation, and smart controls that can be programmed or can learn a consumer’s pattern of use, delivering toasty warm floors when users arrive home.

An example of today’s electric floor warming options: ARDEX FLEXBONE® HEAT In-Floor Heating Systems

And fortunately, ceramic and porcelain tile are excellent choices for radiant heated flooring, said Thomas Utley, Technical Specialist FLEXBONE HEAT/ARDEX Tile and Stone Installation Systems. “They have high thermal conductivity and retain heat better than other flooring choices. The thickness of the tile has little impact on the heat output but the heating time is increased with thicker tiles.”

But like any product, there are things to keep in mind for a successful electric floor warming installation. We surveyed a few of the top electric floor warming manufacturers to get their recommendations for foolproof installations.

Top tips for contractors

What are the top things contractors should keep in mind when working with electric floor warming systems? First of all, “Contractors should be mindful that the desired flooring finish must be compatible and tolerant of the thermal fluctuations these systems can exert, in order to ensure there is no damage to the flooring,” LATICRETE’s International’s Art Mintie, Senior Director of Technical Services, said. 

The Warmly Yours system uses the low-profile Prodeso Heat mat with 3.7 watt electric TempZone heating cables, ensuring proper spacing throughout the project. 

He also cautioned contractors to choose the best type of underfloor heating system that suits their specific needs. “Hydronic (liquid) systems are a popular alternative that rival electric radiant floor heating systems by pumping heated water from a boiler through tubing laid in a pattern under the floor,” he explained. “These systems are also often more expensive and are recommended to be installed at the time of construction, whereas electric radiant floor heating systems are a great retrofitting project that can be done at any time.”

Since these ARE electric systems, Regis Verliefde, Territory Director, NAM of Warmup said, “It’s important for the tile installer to double/triple check coverage and spacing to provide the desired solution for the consumer. While most systems install in a similar way, some are for comfort heat and some are built to heat the whole room. Installers should get familiar with which systems do what and what spacing or insulation to provide on a cold basement slab, for example.” 

Respect Ohm’s Law

The Warmup Alligator tester clips straight to the heating cables and monitors them during installation. 

It’s a good idea to recognize that cutting electric heating elements to make it fit your project is a bad idea, said Julia Billen, owner and president of Warmly Yours. “Because of Ohm’s Law, if floor heating cables are shortened, the resistance of the cables will be correspondingly lowered, which in turn drives up the voltage and wattage,” she said. “This can cause the heat output of the system to go over the limits set by national or local code or, in some cases, even cause the heating system to fail. It’s important to work with a floor heating distributor to ensure you have the right amount of heating elements for your project.”

She also recommends testing the heating elements often with a digital ohmmeter – before, during and after installation. “In between ohmmeter tests, we recommend that you use a continuity alarm that is connected to the heating cables that will sound an alarm if the cable is damaged,” she added. She also advised taking measures to avoid damaging the floor heating cables during installation. 

“One way to avoid this is to install the floor heating mats (if that’s the system-type being used) upside down so that the mat material can protect the cables from damage by trowels or other tools,” she recommended. “Another way is to avoid using metal trowels or floats to apply the thinset on top of the heating system, as these can occasionally damage the floor heating cables.”  

Plan ahead

Carefully calculate the length of heating cable required based on the floor space, minimum clearance from fixed building elements and other objects.

Sean Gerolimatos, Director of Research and Development with Schluter Systems, emphasized preplanning before you start. “It is important to read and understand all product/system and code requirements, create a detailed plan, and execute it diligently,” he said. 

Gerolimatos also suggested, “Carefully calculate the length of heating cable required based on the floor space, minimum clearance from fixed building elements and other objects, and coverage of the heating cable at the manufacturer recommended spacing.” Another great suggestion he offered was to be sure “the owner and any other trades on the project know where heating cable is installed (photos are helpful) to avoid damage during subsequent work.”

Be sure to order the proper amount of heating wire for the job. Shown is the Prodeso Heat system by Progress Profiles.

Domenico Borelli, Vice President and CEO of Progress Profiles America echoed other suggestions, adding that it’s crucial that the “subfloor is suitable for tile installation and electrical radiant heat.” One may think that goes without saying, but establishing a suitable subfloor is essential in any tile installation, especially one that uses electrical mats and cables to provide floor warming. He also emphasized exact, accurate measurements and ordering the proper amount of heating wire for the job. 

ARDEX’s Utley also advised contractors to “Plan to include a second sensor wire in your layout. Only one will get connected initially. The back-up sensor can then easily be connected to the thermostat in the wall without disturbing the flooring installation.”

Even heat distribution is a must

Underfloor heating can develop cold spots when the warmth cannot be evenly distributed. LATICRETE’s STRATA_HEAT™Thermal Pack – used  in conjunction with the STRATA_HEAT electric radiant floor heating system – employs Thermal Diffusion Technology™ to distribute heat uniformly throughout the adhesive. 

In addition, heat sink and heat loss are two primary issues that can arise when installing electric radiant floor heating, LATICRETE’s Mintie offered. “Generally, a backer board with insulation properties can be placed over the concrete slab in order to assist and prevent these from happening. For plywood substrates, installers should conform to TCNA Handbook for Ceramic, Glass and Stone Tile Installation requirements when installing ceramic, porcelain or dimension stone tile finishes over heated flooring systems.

The new Mapeheat system from MAPEI includes membrane, cable, and three kinds of thermostats to choose from. 

Sonya Moste, Product Manager, MAPEI Crack Isolation and Sound Control Membranes also advised contractors to plan for even distribution of heat. “Hot spots and cold spots detract from the experience of a heated floor so consistent watt density is critical,” she said. “Things that make this task easier are pre-built custom mats designed specifically for the individual floor shape or a floor heating membrane with heating cable that has flexible layout requirements (i.e. no restrictions on run length and no requirement for tension loops).” She also suggested “future-proofing the installation with WiFi thermostats featuring connectivity with multiple connected home systems (such as Google Assistant, Amazon Alexa, IFTTT, Nest, Control4, etc.) and also offering an Open API for custom smart home integrations.” 

Don’t underestimate manufacturer support, she advised. “Choose manufacturers that will back their products and the completed installation for 25 years, or more, and make sure the warranty is not pro-rated (in other words, make sure the coverage isn’t for half the value after half of the warranty period has passed),” she said. And a knowledgeable technical support team that offers on-site and telephone consultation is worth its weight in gold.

Working with electricians

To follow code, you will need to work with an electrician to complete this project. It’s essential to coordinate your services for ultimate success. Progress Profiles’ Borelli said, “A 10 minute conversation at the job site will save time and money and aggravation later.” And MAPEI’s Moste pointed out that it’s a good idea to “work with manufacturers that have experience dealing with both trades. The best certification programs will cater to tile contractors and electricians.”

Tile contractors and electricians should test the heating cables at every stage of the installation.

A good suggestion from Warmup’s Verliefde is to leave the product tag with wattage and voltage attached to the lead wire or inside the roughed-in electrical box, ensuring the right voltage breaker is provided for the job. He also recommended that contractors locate where the electrician has roughed-in the thermostat box and start the system at the base of that point on the wall. “And if your system is over 250 sq. ft., have a quick chat with the electrical contractor to discuss power supply and the best location for the power connections,” he added. 

Warmly Yours’ Billen insisted that tile contractors and electricians test the heating cables at every stage of the installation, and record and communicate those readings to each other to ensure the system remains functional at every stage of the process. 

At Schluter, Gerolimatos noted that different floor systems may have different orders of installation, so as he suggested earlier in this story – plan and acquaint yourself with the quirks of the particular system you are working with. 

“It’s also important to establish where the responsibility of each trade begins and ends,” he said. “For example, some jurisdictions allow tile setters to layout the heating cables, where others require the electrician do so.” 

And finally he mentioned that connecting a 120V heating cable to a 240V power source is one of the most common mistakes when installing electric floor warming systems. “This can be easily avoided with a little bit of planning ahead of time,” he explained. “Check the available power source and make sure to order the corresponding heating cable (120V cable for 120V power, 240V cable for 240V power).” 

Use your time wisely

Most of us would agree that there is just not enough time in the day to get everything done. There is always some sort of fire to extinguish, the unexpected phone call that takes longer than planned, or pleasing your customer who wants to add more work to the project just when you were planning to call it complete.

The work is on the schedule and needs to be completed as planned and promised. But how do you squeeze more time out of the clock or jam more stuff into the available time? The answer is time management.  

Wikipedia defines time management as: “The process of planning and exercising conscious control of time spent on specific activities, especially to increase effectiveness, efficiency, and productivity.” Further, planning or forethought is the process of thinking about and organizing the activities required to achieve a desired goal.

In order to apply these principles in the tile trades, an installer must develop a plan of action by either building the project in his or her head prior to beginning the work, or by sketching it out on a piece of paper. Having a plan in place is the roadmap to a successful project completion. 

Plan ahead with a grid pattern for layout

Waiting in line at the wet saw to make two cuts is a huge waste of time. 

The use of a grid pattern for floor tile layout is a good example. It may take a little more time to mark the layout on the substrate, pop key lines, and grid it out, but once in place, all the perimeter cuts can be made. Making these cuts on a snap cutter saves more time. In this case, almost all of the cuts, with the exception of “L” cuts, can be made right where they will be installed. No need to walk to the wet saw, make the cut(s), dry the back of the tile, and walk back to the install point. Additionally, once the mortar is properly mixed, the grid pattern allows multiple installers to work in the same area, which really increases productivity.

When cuts need to be made on a wet saw and the installer is working alone, mark as many pieces that can be safely carried to the saw and make all of them at one time. Making multiple trips to the saw with only one or two cuts can devour a huge amount of time. 

Better-grade materials can save time

Using a better grade of setting materials that have thixotropic (becoming flowable when moved in a back and forth motion) characteristics will yield better mortar coverage and transfer to the back of the tile. Many times, these products will eliminate the need to back-trowel (formerly known as back-buttering) the tile with additional mortar.

Keeping focused

Evaluators of the Certified Tile Installer (CTI) program routinely stress this phrase to the installers preparing to take the hands-on test: “Use your time wisely!”

Something that wasn’t even a factor ten years ago is now a significant drain on the productivity of a tile installation. Not surprisingly, a smartphone and Facebook bring new challenges to the workplace. Everyone needs to be connected these days, but the jobsite should be just that, with nothing to interrupt the thoughts that went into the plan. When focus is lost, so is the valuable time that is needed to get back on track and keep moving. 

One more thought; show up to the job early each day well rested and ready to go. Establish your plan and stick to it.

And finally, the Evaluators of the Certified Tile Installer (CTI) program routinely stress this phrase to the installers preparing to take the hands-on test: “Use your time wisely!” 

Tile and bath safety

With all the beautiful tile available today, it is sometimes difficult to make the perfect choice. However, when considering your selection of a floor tile in a stall shower, many decisions need to be made to ensure a safe environment.

Many times, the tile selection process for a shower floor is focused on the aesthetics of the installation being a beautiful blend of products that will further enhance the overall project. But the primary goal here is to obtain tile that will yield a safe surface on which to stand while using the shower. 

The TCNA Handbook does offer some helpful information that can guide the selection of the appropriate floor tile. Under the header, “Coefficient of Friction and the DCOF AcuTest®”, it states the following: The DCOF (Dynamic Coefficient of Friction) measures the dynamic friction, which is the frictional resistance one pushes against when already in motion. Under this test, a slip occurs when pushing off with more force than the surface can resist. Tile which is tested to this protocol yields a minimum wet DCOF AcuTest value of 0.42 for ceramic tiles for level interior spaces expected to be walked upon when wet. 

A clean crisp look featuring a single slope shower floor leading to a linear drain along the base of the shower seat. Image courtesy of Daltile.

While this test does not identically mimic the process of standing in the shower (not walking) and is not level due to the slope to the drain, it does provide some guidance as to which tile may function better in wet conditions.

The Handbook further makes this statement: “According to the standard, tiles with a wet DCOF AcuTest value of less than 0.42 are only suitable for floor areas that will be kept dry. Polished tiles generally fall into this category.” Caution should be exercised when considering high-fashion polished tiles that are pleasing to the eye, but offer little resistance to slipping, especially when combined with soap, shampoo, and water. 

For years the popular and functional selection of shower floor tiles resided with a 1” x 1” or
2” x 2” mosaic tile as shown in the attached photo. This small facial surface area tile provides a significant number of grout joints that can aid in providing a surface that offers good traction. 

However, today’s consumers are demanding the use of larger tiles that offer a sleek look that slope to a linear drain located either in the center of the floor or at the intersection of the wall. These large-format tiles look great on the shower floor and offer a look not available in the past. Imagine combining a realistic woodgrain plank floor with a gorgeous marble wall that both offer the benefits of a porcelain tile.  

After the tile has been selected and properly installed, the appropriate maintenance regimen must be instituted. Normally, a pH-neutral cleaner will work well for routine cleaning. However, if a residue of soap scum, body oil, shampoo, and/or cream rinse accumulate on the floor surface, the use of a high-alkaline cleaner may be needed remove the build-up. As always, carefully follow the directions on the container to ensure thorough cleaning and a trouble-free tile installation that will stand the test of time.

To waterproof or not to waterproof, that is the question

The TCNA Handbook for Ceramic, Glass, and Stone Tile Installation highlights the building designer’s responsibility to know how each tile installation will be used and maintained, to avoid under-designing an area for the amount of water it will be exposed to. Courtesy of the Tile Council of North America, Inc. (TCNA).

I talk to many people who are not clear on when and where to use waterproofing under tile installations. The most surprising thing I come across is those who think that tile, grout, mortar and backer board are waterproof. Unfortunately, there are many failed installations due to the lack of waterproofing and improper waterproofing, so let’s look at when to consider using waterproofing under tile.

A good place to start is the Tile Council of North America (TCNA) Handbook, which addresses waterproofing in several places. There are specific sections such as the “Membrane Selection Guide” and the “Wet Area Guidelines” that discuss membrane usage. The Membrane Selection Guide outlines several different types of waterproofing, from non-metallic, lead, copper, CPE and PVC. There are also the ANSI A118.10 trowel-applied sheet or liquid waterproof membranes commonly familiar to the tile trades. Sometimes these are referred to as fluid-applied membranes. Once cured, these ANSI A118.10 membranes are designed to provide a continuous membrane that tile can be directly bonded to.

The Wet Area Guidelines section in the TCNA Handbook is a very useful for understanding the requirements for waterproof membranes. In addition to discussing the environmental exposure classification, this section also discusses proper slope required for wet areas, as well as the different types of drains, such as clamping drains and integrated bonding flange drains. One of the most important topics discussed in this section is performing the water test, commonly called a flood test or 24-hour test. Testing the ability for the area to properly hold water is an important factor to know prior to installing tile and is required by certain municipalities.

Many TCNA Handbook methods include the possible use of a membrane, leaving the design professional to determine whether one is needed, based on the expected water exposure.

Within the TCNA Handbook methods, such as F141-19, the diagram shows the option for a membrane and below the diagram it states, “*Use of a membrane is optional. See membrane options.” Does that mean a membrane usage is optional at the discretion of the installer? No, first, it’s important to understand the designed usage of the space and its Environmental Exposure Classification. The Environmental Exposure Classification section in the TCNA Handbook is often overlooked and yet it holds a wealth of information with regards to the intended usage of a space and thus the proper classification. These classifications are divided into two categories, residential (res) and commercial (com). Both the residential and commercial categories are further divided into seven separate classifications, each with its own expected water exposure.  

In the example TCNA F141-19, the area is designed with limited water exposure has a rating of Res1,2/Com1,2. If this space is going to be used as a commercial kitchen for instance, this area is typically designed with limited

Commercial kitchen maintenance practices vary widely. Some are routinely saturated during cleaning and require a membrane.

water exposure in mind, giving it a Com2 usage rating. The difference could be as simple as how the space is cleaned, do they intend to hose down the walls and floor? If so, the area would need to be designed for increased water exposure as outlined in the membrane options within the TCNA F141-19. Typically, in this type of situation, the flashing connections to the walls and any drains need to be addressed to create a complete waterproof system.

As you can see, there are a lot of considerations for the proper selection and use of waterproof membranes. If you have specific questions, contact a membrane manufacturer and they can help with the correct choice of material. Some manufacturers even provide job site support for the proper installation of their material. I’ll leave you with my simple rule of thumb, if it’s going to see water exposure, waterproof it – because in the end it’s cheaper than a failure.

About that grout joint width

There are many factors to consider before selecting an appropriate grout joint width for porcelain and ceramic tiles. Factors that affect proper specification, by way of example but without limitation, include the tile’s dimensional tolerances such as allowable warping and out of square per ANSI A137.1 manufacturing standards, floor flatness, size of the area being tiled, and the presence of movement joints in the subfloor per ANSI A108 installation standards. One also needs to consider exposure to excessive moisture, direct sunlight and temperature swings based on the final use and application. Both vertical and horizontal applications can be affected by all of these factors, which in turn can cause movement and tension in the finished tile assembly. 

There is a general misconception that because ANSI A108 sets its minimum recommended joint width limit to 1/16” – and grout manufacturers produce grouts that can be applied as narrow as 1/16” – that the minimum suitable joint width can also be set to 1/16” for all application types. In some applications, like a kitchen backsplash, a narrow joint may be attainable. However, selecting an arbitrary floor grout joint width as narrow as 1/16” for purely aesthetic reasons, or perceived maintenance, can be extremely problematic not just in terms of the tile assembly’s structure, but also may not be attainable across large areas while keeping adjacent rows aligned. There have been great advancements in manufacturing technologies of both cementitious and non-cementitious grouts as well as grout additives over the years, allowing highly stain-resistant properties to prevent, and in some cases eliminate, the age-old struggle with keeping grout joints clean. 

Manufacturers sort tiles by caliber. Tiles of the same size are closer in caliber.

It is not only important to understand the intent of industry and manufacturers’ recommendations prior to joint width specification, but also understand the function and necessity of grout in a tile application as a whole prior to selecting a joint width. The role of grout is not only to bond adjacent tiles to one another, but also absorb and disperse some of the tension caused by the expansion and contraction of tiles and substrates. Although grout should not be used as a standalone waterproofing measure, it does display repellent properties, that when compromised in a wet application, can lead to other failures. In other words, if the joint width is not filled properly, maintained properly, or of sufficient width, then failures may be inevitable. As such, butt-jointing techniques should never be used. 

ANSI industry standards for tile are written in such a way to account for both manufacturing and installation tolerances to mitigate potential failures and set expectations of what the end result may look like. When going against industry standards and/or manufacturers’ recommendations, failures may include excessive appearance of lippage, cracking, warping, bond failures, water damage and tenting from tension. Provided that the manufacturer and/or distributor that the tiles were purchased from follow ANSI, ISO or other industry standards for manufacturing, then it can be presumed that the tiles supplied will have certain flatness and dimensional tolerances within a particular range. Since these standards allow for facial dimension variations, the joint width needs to properly account for these variances so that grout joint centerlines can remain straight throughout the application and adjacent tile modules don’t touch at any point. The joint width itself may narrow and widen throughout the application to account for facial variations and floor flatness. ANSI A108.02 Section 4.3.8 addresses this by stating the joint width shall be three times the actual variation of the facial dimensions of the tile supplied. 

A larger grout joint is needed for tiles that do not meet the rectified requirements, especially in an offset pattern.

One critical point that is often missed in ANSI A108.02 4.3.8.2 is the additional verbiage that recommends widening the joint of necessity past the standard recommendation to accommodate the specific tile being installed. Without having to measure each tile, it is always best to account for the maximum allowable tolerances whenever possible during specification, which would be approximately 3/16” for pressed porcelain and ceramic tiles and approximately 1/8” for rectified products. This is just a general guide. In some instances the variations in tile dimensions will be minimal, while in other cases they may be riding the maximum tolerance limits or beyond. For example, glazed red-body ceramics are typically developed as a budget-friendly product and may require up to 1/4” joint width depending on the manufacturer’s recommendations instead of the standard recommendation of 3/16” for pressed ceramics due to their inherent size irregularities. With the rise in popularity of long porcelain planks, even though the edges of such tiles may be rectified and the tiles may not have any wedging, the widening of the grout joint width may be necessary to address any inherent warpage that those products tend to display along an edge or diagonal due to their elongated shapes. As such, it may actually be best to install some rectified plank products with a 3/16” joint instead of the generic industry recommendation of 1/8” to help hide any inherent lippage. In other words, due to nuances of manufacturing of certain product types, the manufacturer’s recommendations always prevail over a generic industry guideline to achieve the best end result. 

The final layer that provides guidance in proper grout joint width specification is the advancements and availability of leveling clip systems on the market today that help mitigate against the possible negative effects of tile and substrate flatness. Not only is a clip system used as a spacer, but the wedges’ function is to pull tiles from below and simultaneously push tiles down from the top to create a flatter plane in the finished tile install. When potential lippage and floor flatness are being addressed in this manner, a tighter joint may be achieved provided no other jobsite conditions, as previously mentioned, will negatively affect the floor. When opting to go against industry standards or manufacturer recommendations, especially when using a leveling clip system, the specifier and end user must have an understanding, not only of the inherent nature of certain tile product types, but installation tolerances as well. Leveling clip systems are not a final end-all solution to problems related to inherent warpage and joint width spacing, but they do provide an effective measure to mitigate against the negative effects of lippage and challenges in floor flatness. 

Narrow joints are possible, but only when the tile is well within the sizing and warpage tolerances for rectified tile. Even so, an offset pattern was not selected because a straight lay masks tile warpage (minimizes lippage) whereas an off-set pattern would have highlighted the tile’s warpage by causing greater inherent/unavoidable lippage in the installation, which would be particularly visible when natural light shines in on the installation. Also, the grout closely matches the tile, making the joints seem smaller/less obvious. Even with all of these factors, the grout joints are 1/8” wide, not 1/16”.

How to ensure a successful self-leveling underlayment application 

“Self-leveling underlayment” is a bit of a misnomer because it requires the intervention of a thoughtful installer to ensure the best results. Follow these guidelines to prevent issues in your self-leveling underlayment installation.

1. Select a product appropriate for the installation: Know your installation environment and familiarize yourself with the relevant ASTM standards for strength. A commercial floor subject to heavy rolling loads will require a higher-grade self-leveling underlayment than a floor in a single-family home.

Also, it is critical to understand your project timeline and choose a product that fits within the appropriate schedule. Some products may require 24-48 hours prior to installing tile, while other more premium products are ready to accept flooring in as little as 2-4 hours. Consult product data sheets for information on tensile strength, compressive strength and flexural strength, as well as recommended cure times.

2. Stabilize your substrate: Most products require that all surfaces are fully stable and structurally sound prior to the application of a self-leveling underlayment. For example, wood must be securely fastened with screw-type or ring-shank nails and adhesive because if it shifts, it could cause cracking. 

3. Prepare your substrate: Make sure to plug all floor openings, gaps and cracks and install termination dams to prevent any seepage. Consult with product manufacturers to determine moisture limitations of the self-leveler, adhesive and flooring to determine if moisture mitigation is needed.

If moisture mitigation is required, this must be done prior to installation of the self-leveling underlayment.

TEC® Level Set® 200 was designed for the fast leveling of floors. It is both pourable and pumpable to fit your job needs.

Self-leveling underlayments (SLUs) require the use of a primer prior to installation. Primer retains the moisture within the self-leveling underlayment to properly cure. Secondarily, it acts as a bonding agent to ensure the SLU bonds properly to the substrate. Refer to the primer label for information regarding application methods and dilution per ASTM F3191.

Beyond priming, most self-leveling underlayments require that the substrate be free from any contaminants that may inhibit bond, including oil, grease, dust, loose or peeling paint, sealers, floor finishes, curing compounds or contaminants. Some underlayments will require a certain concrete surface profile (CSP), and in these cases, mechanical abrasion, like shot-blasting, is required. Make sure the substrate is contaminant free and has the necessary surface profile before starting the pour. 

4. Mix properly: Mix your self-leveling underlayment within the water range specified on the bag. Overwatering will lower the strength of the underlayment and can cause cracking and pinholing. Additionally, a white film (efflorescence) may form on the surface of the cured underlayment if the product is overwatered. This film can act as a bond breaker if the mortar bonds to the salts instead of the SLU. Do not over mix it, as this can make it harder to work with and lead to cracking or improper flow. Mix a maximum of two bags at a time when barrel mixing to ensure a proper blend. Follow equipment and product manufacturer’s recommendations when pumping self-leveler.

TEC® Level Set® 200 is walkable in 3-4 hours, making it a great choice for fast turnaround jobs.

5. Be aware of product and environment temperature: Make sure that the temperature of the room is within the manufacturer’s acceptable range. A climate that is too cold or too hot can cause issues, such as increased set time in cool temperatures or reduction in heal time in hot environments. Temperature and humidity will affect flow, working time and set time.

Additionally, the temperature of the powder and the water is crucial. Leaving product in the sun, or in a hot environment may lead to flash setting. In situations where warm product is unavoidable, mixing with cool water may help combat installation issues. 

Whether the environment is warm or cool, acclimating the product prior to mixing is a best practice.

TEC® Level Set® 200 delivers extended 25-35 minute working time without compromising flooring installation time.

6. Use as recommended: Manu-facturers will specify the maximum thickness of their product. Some products allow for addition of aggregate to increase the depth of the pour, while others only allow their product to be used neat. Be sure to use the appropriate aggregate size and amount when extending a self-leveling underlayment. If a surface is extremely uneven in an isolated area, a patch may be necessary, rather than a self-leveling underlayment. Consult with manufacturers to determine the most suitable product for your application. 

Protect from excessive drying due to air movement. Use of fans or other direct air flow is not recommended, as the surface can be prematurely dried, leading to a weak underlayment.

7. Protect your underlayment: Generally, underlayments are not final wear surfaces. They should be protected from construction trade traffic until final floor covering is applied. Traffic without protection can lead to cracking and disbonding. Do not allow heavy or sharp metal objects to be dragged directly across the surface.

A common theme connects these recommendations: noting and adhering to the manufacturer’s instructions. You must read labels and product data sheets carefully to ensure products perform as desired. If you do have questions, you can always reach out to the product manufacturer.

Scribing: demonstrating artistry and craftsmanship in creative tiling

Those familiar with tile recognize that stunning tile installations have stood the test of time and endured as practical works of art for generations and generations.

Today’s tile setters participate in that tradition of precision and artistry with every job. And there are some techniques that take tile craftsmanship to the next level. Scribing is one such technique.

“Scribing is an art form,” said NTCA member Joshua Nordstrom, of Tierra Tile in Homer, Alaska. “It highlights the level of skill, detail, and abilities that you’re capable of.”

Scribing “gives an install a more artistic feel – it’s more personal – which is great for our industry because as tile setters, we are artists, and it’s nice to be able to do something creative to showcase that fact,” agreed Jason McDaniel, NTCA member of Stoneman Construction, LLC, in Tualatin, Ore.

Scribing is done “when a factory tile meets an organic shape such as pebbles, natural stone, or around an irregular shape,” Nordstrom explained. “Pebble scribing is very common because cutting pebbles in a straight line doesn’t look or feel like a natural transition,” McDaniel added. “Over the past few years, it has become more common to see a pebble scribe.

“Personally, because I like to scribe, I decided to do a mosaic hex scribe and see how that would look,” McDaniel said. “It looked amazing and now we scribe everything.”

“Personally, because I like to scribe, I decided to do a mosaic hex scribe and see how that would look,” McDaniel continued. “It looked amazing and now we scribe everything.” 

While there are many ways to customize a project, scribing can make the job truly original. Nordstrom says in his Alaskan community, his clients like to incorporate nature endemic to the area into their tile designs, often in bathrooms and entryways. “I offer my clients a personal touch for their tile install, from an elaborate mural to a simple medallion, he said. “I find that I can sell a scribed mosaic in about six out of 10 jobs. Most people like to add just that little touch to set their home apart from the rest.”

Scribing takes a combination of skills, all of which begin with PATIENCE. “Scribing is a game of patience that requires time and experience to master,” Nordstrom pointed out. “It takes as long as it takes,” said Kyle Gaudet of Flawless Floorz, a NTCA member in Brentwood, N.H., “Take your time – even extra time – until you’re comfortable with what you’re doing.”

 

The essential skill of templating

Nordstrom's Kraken drawing and cut out

Nordstrom’s Kraken traced life size on a Tyvek ‘canvas.’

An essential skill to clean scribing is templating. “I template everything when it comes to scribing a mosaic,” Nordstrom said. “It all starts with a scaled drawing that gets blown up with a overhead projector and traced life size on a Tyvek ‘canvas.’ Once it’s all colored and labeled, I go over it with tracing paper creating each individual template. Once everything is cut and installed on a fiberglass mesh, I lay the mosaic over the field tile, trace it out and scribe it in.”

McDaniel’s first step is templating as well. “I precut all of my tiles for the floor or wall and then I overlay the pebbles or mosaic that I am going to scribe,” he explained. “I trace the outside of the tile with a sharpie and then use a grinder and remove the sharpie mark. Once the scribe is completed I take a diamond pad or sanding disc to ease over the cuts and make them look smooth and finished, taking all of the chips out of the scribed area. I have found that precutting the area and overlaying is by far the easiest method to use when scribing.”

“Pebble scribing is very common because cutting pebbles in a straight line doesn’t look or feel like a natural transition,” McDaniel said.

McDaniel’s pebble scribing

McDaniel didn’t always use this method. “The first scribe I ever did was a pebble scribe,” he said. “I made templates using wax paper, which was grueling and time consuming, and not as accurate as overlaying and tracing. Overlaying and tracing allows you to set the field tile first, letting that area dry. Coming back in the next day and setting your scribe mosaic allows you to make the transition between field tile and mosaic tile perfectly flush, as it should be.”

Gaudet uses a “traditional” 2” piece of the tile for a scribing piece, marking every piece contour by contour. “I also use a 5” and 4” angle grinder, nippers and dry polishing pads,” he said.

 

Scribing tools; dealing with varying thicknesses

In terms of tools, McDaniel scribes everything with a grinder with a 6” turbo mesh blade, which gives him the best accuracy given the amount of plunge cutting necessary in scribing. “The larger blade allows you to go deeper into the tile before you hit your grinder. Saw horses and clamps are a must have to hold the pieces in place. After I finish my scribe, I ease all of my edges with a 100 grit sanding disc, or a Dremel tool for tighter corners. I am aware that Joshua Nordstrom does all of his scribing with a tile saw and I find that to be absolutely amazing!”

Nordstrom's Kraken drawing and tile

After everything is cut and installed on a fiberglass mesh, Nordstrom lays the mosaic over the field tile, traces it out and scribes it in.

In fact, Nordstrom uses a 10” wet saw, resorting to a grinder only if it’s necessary to remove some material from the tile back to achieve the same thickness between different tiles. “I have learned over the years that installing a fiberglass mesh on the backs of my mosaics really simplifies the installation,” he said.

McDaniel said scribes can be mounted on membranes or thin backer board, though he prefers to “screed my scribed area with thinset so that I can adjust each piece meticulously, insuring that I have a consistent grout line that matches the rest of my install. It also depends on what you are scribing. Sometimes glass mosaics can be difficult to deal with, so pre-mounting them is a worthwhile step.”

Considering thickness is key when scribing, and matching the tiles or grinding the tile backs is sometimes necessary to achieve the proper thickness. “Sometimes when installing you may need to use different trowel sizes to accommodate the height difference in the tile,” Nordstrom said.

McDaniel said his greatest scribing challenge was installing pebble mosaics around a large piece of walnut in an entryway.

McDaniel said his greatest scribing challenge was installing pebble mosaics around a large piece of walnut in an entryway.

McDaniel tells about his most challenging scribing task – installing pebble mosaics around a large piece of walnut in an entryway. Engineering expansion and elevations among the four surfaces and four thicknesses was tricky, he said. “With anything tile, planning ahead and having a game plan going in is essential to being successful,” he said. “Having a start and stop point, keeping your area clean, making sure you have expansion, using anti-fracture membranes, uncoupling membranes, better setting materials, non-sag thinsets; all of these things make your job easier.”

Pricing the job is personal. Nordstrom figures out how many hours it will take him to cut and install, price it on an hourly or date rate, and figure in a little extra for margin of error. Gaudet, whose company is new to scribing, said his client was initially resistant to scribing and the associated upcharge. But “after showing him a few of the pieces, he was in total agreement with my opinion to scribe that wall,” and to agree to pay the upcharge due to the look.

McDaniel, though, doesn’t charge extra for scribing. “I have never made money on a scribe,” he said. “I do it because I want my work to stand out. I want to be known as an artist and a craftsman. Maybe someday I will make money from my scribing ability, but for now I am okay with being considered a ‘Tile Badass’.”

In addition to taking your time, starting small and having patience, McDaniel said the most important thing when scribing is to have confidence. “Know that you can do it; know that you are doing something different that is going to stand out when seen.” He also recommended following the work of several tile setters who have been successful with scribing – and reaching out to them for advice: Robert Davis, Mike Soho, Zack Bonfilio, Tom Habelt, Carl Leonard, and Hawthorne Tile. In addition, he recommended viewing the videos and pictures posted in several tile-centric Facebook groups: Global Tile Posse, Tile Geeks, Tile Love 2.0, The Misfit Tilers, and Tilers Talk to get more information and inspiration.

If you are looking to give it a try, here is the first video in a series Nordstrom created on scribing. The remaining videos are available on the NTCA YouTube channel.

OSHA silica standards for construction

Revising Table 1 – now is the time to act


By Tile Council of North America staff

The Occupational Safety and Health Administration (OSHA) has announced plans to reopen the Occupational Exposure to Respirable Crystalline Silica ruling, primarily focused on possible changes to Table 1 of the silica standard. Table 1 is a listing of construction tasks with engineering controls, work practices, and possible respiratory protection that provides compliance certainty for those tasks. Currently it’s comprised of only 18 common construction operations, each with their own limitations. The list can be found at https://www.osha.gov/silica/Table1sect1926.1153.pdf or https://bit.ly/2ZaS0zg. 

The notice to reopen the rule is currently at the Office of Management and Budget (OMB) for review before publication in the Federal Register. A 60- to 90-day comment period is expected once the notice is published. To take advantage of this unique opportunity, companies wanting changes to Table 1 must organize quickly and assemble data to support their requests.

Table 1

If a task is listed on Table 1, and the employer ensures that all requirements are followed, the employer does not have to conduct an exposure assessment for that operation. However, the list is far from exhaustive and includes limitations. For example:

  • Several tasks, including cutting fiber-cement backer boards, are limited to only being conducted outdoors. This excludes not only performing the task indoors, but also in “enclosed areas,” which would include garages and many other partially enclosed locations.
  • Many tasks include only one type of engineering control, often water-based. In some instances, vacuum-based controls are currently available but have not been included in Table 1.
  • Some tasks limit the size of the blades that can be used.

In addition, there are some common activities that are not included in Table 1, such as:

  • Mixing mortar, self-leveling underlayment (SLU), and other silica-containing materials using a variety of powered equipment.
  • Shot blasting for floor preparation.

Excerpt from Table 1 showing exposure control methods required for stationary masonry saws.

Excerpt from Table 1 showing exposure control methods required for stationary masonry saws.

Opportunity for changes to table 1

After the initial announcement to reopen the Occupational Exposure to Respirable Crystalline Silica ruling in late 2018, Tile Council of North America (TCNA) staff met with OSHA to discuss the details of this upcoming action. TCNA’s understanding is that OSHA will be looking for at least two types of changes to Table 1:

  • New additions. Submittals can include proposed categories, engineering controls, and PPE requirements (for example, if supported by data, mortar mixing with a 300-rpm drill equipped with a mixing blade, adding water before powder, and without PPE if under four hours per day).
  • Enhanced equipment requirements. Industry can propose new engineering control requirements for tasks already on Table 1, which could change the PPE requirements. For example:
    • With air filtration or water flow rates set above the current thresholds, perhaps PPE requirements could be less restrictive.
    • Some tasks are currently limited to outdoor use only. With data from indoor operations, it may be possible to show that operations conducted indoors, or in enclosed areas, are also below the action level of the rule for certain tasks.

Scoring and snapping is not currently listed in Table 1

Scoring and snapping is not currently listed in Table 1, however in their FAQs, OSHA lists the use of score and snap cutters (or tile splitters, as they refer to them) as one of the activities not expected to expose workers to silica levels of concern.

Beyond adding tasks to Table 1, companies can also use this opportunity to clarify issues they identified through efforts to implement the rule. For example, some companies have raised the question of how to differentiate between a grinder and a saw, especially when the same piece of equipment can be used in both capacities. Grinders and saws are currently treated differently on Table 1. While presumably the difference lies in whether a saw blade or grinding wheel is attached, with Table 1 being revised, that can be clarified by OSHA with no ambiguity for the OSHA inspector and installation company.

Mixing mortar is not one of the 18 construction tasks listed on Table 1.

Mixing mortar is not one of the 18 construction tasks listed on Table 1. Companies that desire changes to Table 1 should prepare now by formulating their request and evaluating their data.

Immediate benefits

The process to potentially change Table 1 will be lengthy, with revised standards likely not out for at least a year. However, data provided to OSHA for changes to Table 1 may be immediately useful as “credible data” when assessing exposure to employees, which is required by the standard for all tasks not following Table 1 requirements.

Prepare now

The window to revise Table 1 is relatively narrow. Given OSHA’s schedule, we expect the notice requesting data to be published this summer, with the 60- to 90-day comment period extending into early fall. Companies that desire changes to Table 1 should prepare now by formulating their request and evaluating their data. If additional data is needed to fully characterize exposure, the effect of controls, or required PPE, companies need to identify that right away to collect the required information.

More Information

For more information on the OSHA silica standard, a convenient list of frequently asked questions is available at: https://www.osha.gov/dsg/topics/silicacrystalline/SilicaConstructionFAQs.pdf or https://bit.ly/2XFAcfe. 

Important note 

This article is to help raise awareness of what TCNA staff believe are important issues for the reader. Please understand, however, that these issues often involve complex regulatory issues that are not easily summarized and that may vary in application based on specific facts and circumstances. Therefore, this article is offered as is, for informational purposes only, and readers should not rely on it for legal or other professional advice. Readers should conduct their own review and seek appropriate professional advice for their specific
circumstances. 

Uncoupling membranes methods and standards: a timeline

In 1987, a new product category was launched in the North American Tile industry called “Uncoupling Membrane.” The product – an orange membrane – was made of polyethylene, ribbed in one direction and had a polypropylene mesh heat-bonded on the underside. This product was only 3/16” (4.5 mm) thick and 3’ 3” (1 m) wide and only weighed 45 lbs. (20.4kg) for a 323 sq. ft. (30 sq.m.) roll.

F147

Surprisingly, one of the most popular uses of this very flexible and non-rigid membrane was over plywood substrates, including over a single layer of plywood. In 1999, the first detail for a “Proprietary Membrane” with double layer of wood subfloor on 24” (600 mm) on-center (o.c.) joist spacing was introduced to the TCNA Handbook (F147). Then, only two years later in 2001, a second detail was added to the Handbook for going over a single-layer plywood floor on 19.2” (480 mm) o.c. joists with an “uncoupling system.” There was no reference to the manufacturer under limitations. The term “uncoupling” was substituted for “proprietary membrane,” and a definition was added to the prologue:

F148

“Uncoupling Systems: A system that separates the finished surface from the substrate to allow the independent movement between the two and prevent the transfer of stresses to the tiled surfaces.” 

For those of you who attended that meeting in Clemson, S.C., you will remember that this was the year that the TCNA Handbook Committee voted to approve removal of anything in the Handbook that had proprietary names, which included the section for “Floors Sound Rated.” Then around 2006-2007, a directive was issued to describe a “DITRA”-like product. This definition resulted: 

“Uncoupling membrane: A plastic membrane system geometrically configured to provide air space between the tile and the substrate to allow independent movement between the two and limit the transfer of the stresses.” 

F128

The last detail added to the TCNA Handbook for uncoupling was in 2007 for “Young Concrete” Detail F128. The concern with young/green concrete is that the concrete slab has large amounts of residual moisture that still need to be released from the concrete. This release of moisture can affect the curing of the mortar and the grout. Many crack-isolation/waterproofing membranes – specifically those membranes that are flat – have limited resistance to pressure from moisture since there is nowhere for the moisture to be released. This in turn creates pressure that can cause the membrane to bubble or debond from the concrete slab. The TCNA Handbook declares that an uncoupling membrane must have free space or empty cavities on the underside of the membrane that inherently allow for moisture/vapor release and eventually equalization. 

The TCNA Handbook prologue uncoupling definition was updated again in 2014 to include: 

“The uncoupling membrane must achieve 50 PSI or greater shear bond strength in 7 days per the test method in ANSI A118.12 Section 5.1.3.”

This addition was in response to the concerns conveyed by labor and some forensic consultants that there were certain so-called “uncoupling membranes” that were failing to the extent of several millions of dollars for repair and damages. The main mode of failure was traced to the bond between the substrate (majority plywood) and the underside of the membrane where the fleece/mesh or other had delaminated. Until an ANSI standard is created for uncoupling, this requirement is a reasonable stop-gap to identify those membranes that are not performing. 

The look of uncoupling has changed over the years but the basic criterion has remained the same: a configured membrane with open-air space to allow for independent movement between the tile and the substrate. Some of the newest additions to the uncoupling category now incorporate a floor warming system and have an optional integrated sound control and thermal break (for quicker heating reaction time).

The need for a standard

Shear testing an uncoupling membrane in the lab using the Instron machine.

 

The need for an ANSI standard has become more essential in North America than ever before, with the proliferation of new uncoupling membranes that have emerged in the market recently. The good news is that the Materials and Methods Standards Association (MMSA) has had a subcommittee that has been working on developing a standard now for several years. In fact, a draft standard has been prepared and will be presented at the next Total Solutions Plus (TSP) conference this year being held in Nashville, Tenn., October 26 – 29. Those companies, organizations and associations involved in this effort include: ARDEX Americas, Custom Building Products; ISOLA; LATICRETE; MAPEI; NAC Products; The Noble Company; Schluter Systems, LLC; and TCNA. Most of the details in the TCNA Handbook that were identified earlier will be part of the testing criteria. In addition, “Point Loading” and “Fungus/Microorganism Resistance” will be included. Two additional testing criteria under development are vapor transmission and shears to evaluate the stress/strain relationship between uncoupling membranes and other membranes that are flat. This testing has been an international effort that has displayed some promising results.

Uncoupling membrane in a commercial building.

 

In addition to the MMSA subcommittee working on an uncoupling standard, the International Organization for Standardization (ISO) has established WG 11 “Uncoupling Membranes for Ceramic Tile Installation” under the auspices of TC-189 (Technical Committee for Ceramic Tile). Some of the same participants are in both committees, so there has been very good communication and collaboration to ultimately achieve the best standards for both organizations. Other areas that are being pursued by the ISO group are “tensile” and “compression” testing.

In summary, uncoupling membranes have come a long way since the introduction of the very first membrane in 1987. Use of these membranes has proliferated over a huge array of substrates and conditions, allowing the tile industry to complete successful installations over some of the most challenging applications. The performance standards for uncoupling have been a long time coming, but creating a suitable standard for a product that works more off of physics than chemistry is not an easy or simple task.  

Uncoupling membrane in a commercial building with large format tile.

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